# -*- coding: utf-8 -*-
"""
Created on Thu Jul 14 19:36:33 2016

@author: saninkyu
"""

def main():
    checkers = CheckersBoard()
    print(checkers)
    
    chess = ChessBoard()
    print(chess)
    
    
BLACK, WHITE =  ("BALCK","WHITE")
class AbstractBoard:
    def __init__(self,columns):
        self.board = [[None for _in range(column)]for_in range(rows)]
        self.populate_board()
        
    def populate_board(self):
        raise NotImplementedError()
        
    def __str__(self):
        squares = []
        for y, row in enumerate(self.board):
            for x, piece in enumerate(row):
                square = console(piece, BALCK if (y+x) % 2 else WHITE)
                squares.append(square)
            squares.append(square)
        return "".join(squares)